diff --git a/calcs/propState.js b/calcs/propState.js
new file mode 100644
index 0000000..5077688
--- /dev/null
+++ b/calcs/propState.js
@@ -0,0 +1,40 @@
+const _ = require('lodash')
+
+module.exports = function (app, plugin) {
+  var engines = plugin.engines
+
+  app.debug('engines: %j', engines)
+
+  return engines.map(instance => {
+    return {
+      group: 'propulsion',
+      optionKey: instance + 'state',
+      title: `${instance} propulsion state (based on revolutions)`,
+      derivedFrom: function () {
+        return [
+          'propulsion.' + instance + '.revolutions'
+        ]
+      },
+      calculator: function (revol) {
+        const currentState =
+          app.getSelfPath('propulsion.' + instance + '.state.value') || 'none'
+
+        if ((revol > 0) && (currentState !== "started")) {
+          return [
+            {
+              path: 'propulsion.' + instance + '.state',
+              value: "started"
+            }
+          ]
+        } else if ((revol == 0) && (currentState !== "stopped")) {
+          return [
+            {
+              path: 'propulsion.' + instance + '.state',
+              value: "stopped"
+            }
+          ]
+        }
+      }
+    }
+  })
+}